The present invention relates to method and apparatus that detects the peak amplitude of pulses. More specifically, the present invention relates to method and apparatus that detects the median peak amplitude of a burst of pulses.
Peak detection of signals is commonly used in many electronic applications. One such application is found in computer disk drives. Typically, the disk drive includes, among other things, a pick-up head that reads data from various tracks on the disk and a servo controller that properly positions the pick-up head over a track of data. The information used by the servo controller to properly position the pick-up head is contained in the amplitude of specialized servo signals contained at various locations on the tracks of data. The pickup head detects these servo signals and transmits them to the servo controller. Then, the servo controller detects the peak amplitude of the servo signals to determine whether the pick-up head is properly positioned over a data track.
In some systems, the servo control signals consist of four bursts of sinusoid signals, with each burst including five to ten sine waves. Such a burst of pulses is illustrated in FIG. 1. In such multiple pulse systems, it is necessary to determine the amplitude of the pulses in the bursts.
One conventional way to do this is to use a single peak detector to monitor each burst of sinusoids. In accordance with this technique, the peak detector is always on so that the largest peak in the burst is determined. Unfortunately, the individual sinusoidal pulses are prone to noise, so that this technique is less than desirable.
In a second conventional technique, the individual peaks are detected separately and then averaged, thereby reducing the effects of noise. There are, however, several disadvantages to this technique. For example, this technique is very sensitive to pulse "drop outs," which occur with some regularity. Also, this technique requires expensive precision linear analog circuitry.
Accordingly, it is an object of the present invention to detect the peak amplitude of a burst of pulses so as to provide immunity to noise and pulse drop-outs.